SUMATRAN RHINOS

"HAIRY" RHINOS

In addition to being the smallest and hairiest of the rhino species, Sumatran rhinos are also the most prehistoric and loosely related to the extinct woolly rhino.

As with Javan rhinos, this species is on the verge of extinction due to a catastrophic decline. Sumatran rhinos live in dense jungle and are few in number, but the birth of a calf to Rosa, a captive born Sumatran rhino at Way Kambas National Park, Indonesia in March 2022 has rekindled hope for future births.

Facts

Scientific name

• Dicerorhinus sumatrensis

"Dicerorhinus”: from the Greek di, meaning “two” and “ceros”, meaning “horn” and “rhinos”, meaning “nose” and “sumatrensis” referring to Sumatra

Sub-species

• Western Sumatran rhino (Dicerorhinus sumatrensis)

• Eastern (Borneo) Sumatran rhino (Dicerorhinus sumatrensis harrissoni)

• Northern Sumatran rhino (Dicerorhinus sumatrensis lasiotis)

Conservation status

• Western: Critically endangered

• Eastern (Borneo): Listed as critically endangered by the IUCN, but only two or three are believed to exist

• Northern Sumatran: Assumed extinct

Population

• The exact number is unknown. The Indonesian government's official estimate is no more than 80 individuals. However, the African Rhino Specialist Group estimates the actual figure is closer to 34-47 (correct as of September 2024).

Population increase/decrease

• The eastern (Borneo) Sumatran rhino was declared extinct in the wild in Malaysian Boneo in April 2015. There are thought to be 2 or 3 left in Kalimantan, the Indonesian side of Borneo including a captive female named Pahu.

• An internal assessment carried out by the Asian Rhino Specialist Group (AsRSG) estimates the population has declined around 13% between 2017 and 2022. Their inhospitable habitat, low numbers and fragmented population complicate tracking and conserving, but also mating.

Current range, habitat & diet

• Current range: Only found on the Indonesian island of Sumata (except the 2 or 3 in Kalimantan) at Way Kambas National Park, Leuser Ecosystem and Bukit Barisan National Park, Sumatra

• Habitat: Dense tropical forest, both lowland and highland, preferring swamps and areas of dense vegetation

• Diet: Twigs, leaves, shrubs and fruit (especially wild mangoes and figs)

Historic range

• Once prevalent in the foothills of the eastern Himalayas, India, Bhutan, Bangladesh, Myanmar, Laos, Thailand, Malaysia, Indonesia and southwestern China as well as the Indonesian islands

Average lifespan

• Approximately 30-40 years although a female Sumatran rhino called Bina celebrated her 42nd birthday in January 2023.

Physical characteristics

• Dark orange-red-brown skin colour with short, bristly hair which helps mud cake their bodies to protect their skin.

• Captive rhinos have a denser covering of hair due to less abrasion from vegetation

• Calves are born with a dense covering of hair which turns darker and becomes more bristly as they age

• Two distinctive skin folds before the front and after the hind legs

• They're adept at negotiating steep slopes and mountains

• Weight: 500-950 kg

• Body length: Up to 250 cm

• Height (to shoulder): 120-150 cm

Reproduction

• Gestation: 15-16 months

• Birth numbers: Single calf

• Birth interval: 3-4 years

• Female sexual maturity: 6-7years

• Male sexual maturity: 10 years

Social characteristics

• Usually solitary, except for females with small calves and brief periods of courtship

• Males have territories up to a range of 50 km²

• Arguably the most voiciferous of the rhino species, with a wide selection of sounds including eeps, whale and whistle-blows which contain high level infrasound that would be advantageous for use in the rhino's forest habitat

Rhino horns

• Front horn: 25-80 cm

• Rear horn: Approximately 10 cm